Sprue former



/1 w. G. MAISON 2,011,818

' SPRUE FORMER Filed July 21, 19:55

Mllllllll! INVENTOR,

Patented Aug. 20, 1935 UNITED STATES PATENT OFFICE SPRUE FORMER WilliamG. Maison, San Francisco, Calif.

Application July 21, 1933, Serial No. 681,513

1 Claim. (01. 22-162) This invention relates to improvements in spruetop 3 concentric with the circles 2, which forms formers and is used bydentists and others, who a crucible when the investment is poured uponit. do small castings, to hold the sprue and to form The dome 3 isformed with a central vertical a perfect crucible for the molten metal.bore 4 which extends downwardly through the 5 The principal object ofthe improvements is entire thickness of the main body I and is adapted 5to provide a sprue former capable of gripping to receive a dental burr5, (shown in broken lines the groove or key at the large end of a dentalFig. 2), when used as a sprue. The head or burr (with the head orcutting blades removed), cutting blades of the burr 5 are removed so aswhen used as a sprue, so as to facilitate the to form a point or acontinuation of the tapered handling of delicate wax patterns for smallcastshank which when heated is attached to the wax 10 ings commonly usedin dentistry such as inlays, pattern. Positioned below the lower end ofthe crowns, etc. bore 4 and in space relation thereto is a lug 6 Otherobjects are to enable the user to easily rigidly attached to the bottomsurface of the pick it up, set it down, or otherwise manipulate body Iand so formed as to intercept the lower it, and to release thecontra-angle dental burr end of the burr 5. Legs 1 support the main body15 (with the head or cutting blades removed) when l in an elevatedposition on the table or work used as a sprue from the body of the sprueformer bench allowing the sprue former to be easily with ease andrapidity, eliminating the necessity grasped and handled by the operator.A lever B of having to tap the base to free the sprue is fulcrumed onthe base of the body I adjaformer from the casting ring and investment,cent to lug 6 by the screw 9. The end H] of the 20 thereby eliminatingthe cause of possible damage lever 8 extends parallel to and beyond thebase to the investment around the sprue. of the body I and is curved toform a handle ll With the above and other objects in View, the which isadapted to contact a projection 12 on invention consists of the novelconstruction and the periphery of the body I. The end l3 of thecombination of parts hereinafter described, illuslever 8 is formed witha notch M of smaller (11- 25 trated in the accompanying drawing, and setmension than the bore 4 and is adapted to engage forth in the claimhereto appended, it being the groove on the lower end of the burr 5 andunderstood that various changes in the form, serve as a latch when thehandle H contacts the proportion, material, size, and minor details ofprojection I2. construction within the scope of the claim may I am awarethat prior. to my invention sprue 30 be resorted to without departingfrom the spirit formers have been made in various sizes and maorsacrificing any of the advantages of the interials operating to grip thesprue pin or wire, vention. but none have been invented to grip thegroove To more fully comprehend the invention, referor key at the largeend of a contra-angle dental ence is directed to the accompanyingdrawing burr. I, therefore, do not claim such a com- 3 wherein:--bination broadly.

Fig. 1 is a top plan view of my invention. I claim:--

Fig. 2 is a sectional view taken on line 22 of A device for the purposedescribed comprising Fig. 1. a base formed with a plurality of raisedconcen- Fig. 3 is a bottom view of the sprue former tric circles on itsupper surface, a bore extending 40 showing the latch or lever in anengaged posithrough the said base, 2. lug formed on the under tion.surface of the said base and extending below the Fig. 4 is the same asFig. 3 except that the lower end of the said bore in spaced relationlatch or lever is shown in a disengaged position. thereto, the said lugbeing adapted to intercept Referring more particularly to the drawing, adental burr, the head or cutting blades of which 45 wherein likecharacters of reference designate have been removed, or a mounted stoneshank, corresponding parts, the base or main body porthe mounted pointof which has been removed, tion I is formed on its upper surface with apluwhen placed within the said bore, and means for rality of raisedconcentric circles 2, adapted to fit releasably retaining the said burrshank against 60 various sizes of casting rings. Extending upthe'saidlug.

ward from the circles 2 is a spherical dome or WILLIAM G. MAISON.

